• Welcome, Guest! We hope you enjoy the excellent technical knowledge, event information and discussions that the BMW MOA forum provides. Some forum content will be hidden from you if you remain logged out. If you want to view all content, please click the 'Log in' button above and enter your BMW MOA username and password.

    If you are not an MOA member, why not take the time to join the club, so you can enjoy posting on the forum, the BMW Owners News magazine, and all of the discounts and benefits the BMW MOA offers?

Slipper Clutch and Friction Zone

chewbacca

New member
I have a 2016 R1200GS LC. I have experienced several occasions where getting what should be a normal friction zone slippage and actuation of the slipper clutch seem to be have problems. It does have shift assist and it does have a slipper clutch. This is not my first bike with a hydraulic clutch.

The best example I can give is making a climbing hairpin right turn where you have to be in first gear and going very slow. You feel the bike go into slipper clutch slipping and then just lurch into fully engaged clutch action. This thing shows it evil head at the worst times too.

Anyone else experience this? Any recommendations?
 
A slipper clutch keeps the rear wheel from losing traction under heavy engine braking. It does nothing during acceleration or at low speeds. Quite a few Wethead riders have reported inconsistent clutch engagement, but it's not due to the slipper clutch.
Best suggestion would be to practice your low speed turns,using a counterweighting body position, possibly maintaining light rear brake pressure, and leave the clutch fully engaged.
 
Does the clutch slip in other situations? For example, start to go up a steep hill and then accelerate hard.
 
A slipper clutch keeps the rear wheel from losing traction under heavy engine braking. It does nothing during acceleration or at low speeds. Quite a few Wethead riders have reported inconsistent clutch engagement, but it's not due to the slipper clutch.
Best suggestion would be to practice your low speed turns,using a counterweighting body position, possibly maintaining light rear brake pressure, and leave the clutch fully engaged.

I totally agree that it "should be" decel only. How the boys from the Black Forest implemented the clutch can make that a totally differnt situation. There is almost no words to describe the event. You start to slip it like you were in a normal friction zone, but it starts making a chattering like sound and becomes herky jerky like it trying to engage then it jumps into fully engaged and is ready to launch the front wheel because it has too much power from throttle used to make it slip in the friction zone. It is NOT an instantaneous event. This chattering lasts for a couple of seconds before it tries to dump you into full engagement. So far I've had one person telll me of an MCN article describing this when the LC's first came out. I have not seen it and can't find it ---yet.
I have been riding since 1966 or so. Only one had a dry clutch. In the last 12 or so years 5 have had hydraulic clutches. This is my first slipper clutch and it works just fine, or I think it does on decel. I have never had this chatter thing ever before. With that said it still could be a technique thing using the friction zone properly. Who knows, just trying to find out if I'm the Lone Ranger having this problem. Actually this only occurs in very slow situations with a higher than normal load like the climbing turn. There was one other event that I can remember where it happened. Should have been a normal pull out from a stop. I started out in third or forth gear (you can call me stupid, I did) and the same thing happened until I got it back into first.
 
You start to slip it like you were in a normal friction zone, but it starts making a chattering like sound and becomes herky jerky like it trying to engage then it jumps into fully engaged and is ready to launch the front wheel because it has too much power from throttle used to make it slip in the friction zone.

I know the friction zone moves a bit as the bike warms up, fairly quickly, but beyond the reality the zone is quite narrow, I've not noticed anything like you describe. Either you need finer control over that narrow range, or something's amiss w/ your clutch mechanically.
 
I found the following in an MCN article directed at the wethead clutch:
"they also have an unfortunate centrifugally energized
pressure plate design that creates control difficulties during hard
launches. Attempt a quick start on the new water-head, and its
clutch will bounce in and out of engagement, making the bike
hop instead of drive forward
."
In another review of an RT there was this:
"My only complaint is that, when using the clutch, I found its very narrow friction zone at the end of the lever’s throw difficult to manipulate. Slow speed maneuvering was met with a herky-jerkiness I hadn’t mastered by the end of our ride."
http://www.motorcycle.com/manufacturer/ ... -ride.html

The highlighted sections above seem to be describing exactly what I was experiencing.

When I checked my res level, a bunch of fluid came out indicating it was over filled. There was a thread on AdvRider that point to the tune of several pages. So I think we are getting at the heart of the matter. Whether the slipper function has anything to do with the issue is mute, it is becoming clear that the clutch unit on a GS probably has a mechanical problem in its design.
 
I found the following in an MCN article directed at the wethead clutch:
"they also have an unfortunate centrifugally energized
pressure plate design that creates control difficulties during hard
launches. Attempt a quick start on the new water-head, and its
clutch will bounce in and out of engagement, making the bike
hop instead of drive forward
."
In another review of an RT there was this:
"My only complaint is that, when using the clutch, I found its very narrow friction zone at the end of the lever’s throw difficult to manipulate. Slow speed maneuvering was met with a herky-jerkiness I hadn’t mastered by the end of our ride."
http://www.motorcycle.com/manufacturer/ ... -ride.html

The highlighted sections above seem to be describing exactly what I was experiencing.

When I checked my res level, a bunch of fluid came out indicating it was over filled. There was a thread on AdvRider that point to the tune of several pages. So I think we are getting at the heart of the matter. Whether the slipper function has anything to do with the issue is mute, it is becoming clear that the clutch unit on a GS probably has a mechanical problem in its design.

Ain't technology wonderful. There is no excuse for this behavior. We've had workable clutches for 100 years without this mickey mouse. It is shameful.
 
I'm still trying to remember to not use the clutch. Someday, I swear, I'll actually do it. As is, clutch-shift-clutch, every time. Can't stop doing it.
 
Ain't technology wonderful. There is no excuse for this behavior. We've had workable clutches for 100 years without this mickey mouse. It is shameful.

Worry not. Within a year or two there will be an optional bit of technology available, at a heart stopping cost, that will overcome the faults of the clutch.
 
I haven't experienced any of the above symptoms. The small friction zone is hard to get right in slow maneuvers plus the ride by wire throttle is hard to "finesse". But other than these issues my clutch has been rock solid.
 
I have recently ridden VA 80 just south of US19, sections of TN 66 and 70 north of Rogersville, TN 31 and 63 between Middlesboro and US11. ALL had major climbing right hand switch backs. NO problems. Having the clutch in position one, closer to the grip and filling the fluid to the proper (it WAS definitely over filed) level "may" have contributed to this but can't say anything for sure except "absolutely no issue" with hopping. Contributing factors were: I was more aware of the situation and prepared for these turns, I got into first gear early and moved far left across the center line (no traffic, these are not heavy traffic roads), I did not worry about hitting the inside apex where it was most steep and if I went left of center I was prepared to head for the ditch on the left if a car popped up (most of these turns that was not a high probability event.)
I was very observant of how the friction zone was engaging and played with it quite a bit. It did seem way more predictable. This may not seem to directly related but I have gone to church. LOL No their empty parking lot and practiced both left and right U turns feathering both the clutch and rear brake. This seems to be giving more confidence in slow tight stuff. For me, the problem seems solved, however I am making sure it is being noted by my service manager.
 
I haven't experienced any of the above symptoms. The small friction zone is hard to get right in slow maneuvers plus the ride by wire throttle is hard to "finesse". But other than these issues my clutch has been rock solid.
******
Yes, it took me quite a while to master my 2016RT's clutch. Limited friction zone and w/the fly by wire throttle it took many attempts to get smooth starts from 1st gear.
 
I haven't experienced any of the above symptoms. The small friction zone is hard to get right in slow maneuvers plus the ride by wire throttle is hard to "finesse". But other than these issues my clutch has been rock solid.

I have no troubles w/ the clutch from brand new '16 to now 27K miles--it's wonderful. I love the easy clutch level pull force required. You just need to respect its narrow zone especially when the bike is cold.
 
I have no troubles w/ the clutch from brand new '16 to now 27K miles--it's wonderfulThat is a sampling group of one experience. I love the easy clutch level pull force required The lever effort has never been the issue or even mentioned in this discussion. You just need to respect its narrow zone especially when the bike is cold.JUst because there is a poor design OR implementation does not mean you have to RESPECT it

There were two issues in this post from the beginning. First was what BMW calls a "judder" issue, which I will come back to. Then there was the issue of friction zone. I mistakenly linked the slipper function to the problem because this was a new clutch on the wethead which had the slipper function. Adding that function to the wethead wet clutch may or may not have caused the original issue.

MCN has posted reviews of both the GS and RT where they experienced the judder issue. I had numerous replies on several forums complaining of the "wonderful" friction zone and then a group started to form talking about the over fill reservoir issue. On my GS, sampling group of one, the clutch reservoir WAS DEFINITELY over filled. I corrected that AND in the process discovered that the first lever adjustment point worked really well for me. Those two items FOR ME solved the friction zone issue. I do NOT know if the the judder issue is solved but I have not experienced it even when in situations where I had run into it before. Now this is the kicker! Finding a BMW service manager who recognizes that judder exists is like finding the Holy Grail. Well, on the 2017 wethead transmissions there is NOW a judder damper. Hmmmm. Do you think they put that on for decoration?
 
There were two issues in this post from the beginning. First was what BMW calls a "judder" issue, which I will come back to. Then there was the issue of friction zone. I mistakenly linked the slipper function to the problem because this was a new clutch on the wethead which had the slipper function. Adding that function to the wethead wet clutch may or may not have caused the original issue.

MCN has posted reviews of both the GS and RT where they experienced the judder issue. I had numerous replies on several forums complaining of the "wonderful" friction zone and then a group started to form talking about the over fill reservoir issue. On my GS, sampling group of one, the clutch reservoir WAS DEFINITELY over filled. I corrected that AND in the process discovered that the first lever adjustment point worked really well for me. Those two items FOR ME solved the friction zone issue. I do NOT know if the the judder issue is solved but I have not experienced it even when in situations where I had run into it before. Now this is the kicker! Finding a BMW service manager who recognizes that judder exists is like finding the Holy Grail. Well, on the 2017 wethead transmissions there is NOW a judder damper. Hmmmm. Do you think they put that on for decoration?

Well, it's no problem for me, judder, friction zone. What I do not appreciate is the N>1st gear clunk, so I avoid it. It clearly is an engineering design defect IMO. Fortunately one can avoid it, but one also feels the basic problem when downshifting into first as well, the lack of separation when the clutch is pulled. What's weird to me is: I can be decelerating in 2nd gear as I'm approaching a full stop. Now if I put the bike in N, then let the clutch out while I'm rolling along at just a few MPH, then if I pull in the clutch lever and apply gentle downshift pressure it slips into first with zero clunk. Why can't I come to a full stop then pull in the clutch and put it in 1st and not have it clunk? Just rolling a few MPH prevents the clunk. I wonder what the basic cause is for this? We note when the bike is cold and ambient less than about 60F, there is no N to 1st clunk. It must have to do w/ heat-related expansion of adjacent parts, despite oil that gets a little thinner as it heats up.
 
What I do not appreciate is the N>1st gear clunk, so I avoid it. It clearly is an engineering design defect IMO.
I just went into the garage to see what the clunk was like on my bike. I don't even think about it because as I had thought before I tried it, it isn't that bad on mine. Now when I had a 2011 GS it was a significant clunk. On GS's it seems to be just a normal fact of life kinda thing. Heard people talk about it for a long time. On three Triumph triples and two FJR's it was never as pronounced as on the GS's. IIRC no bike I ever had had a consistent clunk like the GS either. I feel a lurch when it goes into first in addition to the clunk. For me, it ain't no big thing as long as it stays the same and doesn't get louder and the bike doesn't start to move.
 
Well, it's no problem for me, judder, friction zone. What I do not appreciate is the N>1st gear clunk, so I avoid it. It clearly is an engineering design defect IMO. Fortunately one can avoid it, but one also feels the basic problem when downshifting into first as well, the lack of separation when the clutch is pulled. What's weird to me is: I can be decelerating in 2nd gear as I'm approaching a full stop. Now if I put the bike in N, then let the clutch out while I'm rolling along at just a few MPH, then if I pull in the clutch lever and apply gentle downshift pressure it slips into first with zero clunk. Why can't I come to a full stop then pull in the clutch and put it in 1st and not have it clunk? Just rolling a few MPH prevents the clunk. I wonder what the basic cause is for this? ...
Different people have different levels of sensitivity to mechanical sounds, but if your bike sounds similar to the "typical" wethead, than there is nothing actually wrong with the tranny-clutch setup, it is just that BMW has never concerned itself much with masking the mechanical sounds of it's transmissions. They are normal sounds that are simply engineered out of most other bikes. Some prefer to have the more raw sound of the BMW tranny as it provides a quicker audabile clue to any tranny issues, while others prefer to have a more insulated and removed experience. Just a matter of which flavour you prefer.

... We note when the bike is cold and ambient less than about 60F, there is no N to 1st clunk. It must have to do w/ heat-related expansion of adjacent parts, despite oil that gets a little thinner as it heats up.
It is the reverse of what you are thinking. As the oil heats it gets thinner (both in it's amount on the parts and in it's viscosity). Therefore it has less of a dampening affect on the sound.


I just went into the garage to see what the clunk was like on my bike. I don't even think about it because as I had thought before I tried it, it isn't that bad on mine. Now when I had a 2011 GS it was a significant clunk. On GS's it seems to be just a normal fact of life kinda thing. Heard people talk about it for a long time. On three Triumph triples and two FJR's it was never as pronounced as on the GS's. IIRC no bike I ever had had a consistent clunk like the GS either. I feel a lurch when it goes into first in addition to the clunk. For me, it ain't no big thing as long as it stays the same and doesn't get louder and the bike doesn't start to move.
Depending on the amount/degree of the "lurch" it could be normal (if it is minor and goes away immediately) or an adjustment issue (if it produces a constant pull on the bike).

As for the 2011 GS there is very little to compare as it uses a dry-clutch which makes a significant difference on sound and feel to a wet-clutch. What is common is that BMW in the past have never worried too much about tuning out "normal" sounds and cluncks on their Boxers, that occur in all trannies but are engineered out by most everyone else, so when they went to the wet-clutch on the Boxer they didn't tune that out as much as they have on their G, F S, and K models.
 
Alan,
Excellent post; however, sound was never a part of the OP. Sound was an inserted issue just a few posts ago. The "judder" does have a sound associated with it but that was never the issue or even mentioned IIRC. The issue was that the clutch engaged then disengaged in rapid succession causing the front end to hop. There was NO slipping of the clutch between engagement and disengagement. It is like a machine gun, engaged, disengaged, over and over until you pull the clutch lever all the way in. You start to slip the clutch in a normal fashion then the judder begins. It's not fun because it usually occurs in places where balance is an issue. Whether the elves in the Black Forest think that is just something for one to get accustomed to or not may be subject to a readjustment of thinking if NHTSA gets involved. If you ever experience it, it will be obvious it is a very dangerous event. Judder is like alcoholism, the first step is to get out denial and admit it exists.

P.S. - the lurch is not significant. Lots of bikes do it to some degree. Yes you can compare dry and wet clutches if all you are comparing is the sound. The 2011 had a louder clunk than the 2016, just a fact.
 
Back
Top